July 1, 2009

GPS Tags Help Researchers Explore Mysterious Puffin Decline

The number of puffins at one of the UK's key colonies has mysteriously fallen by a third and scientists are now using hi-tech tags to get an insight into why it may be happening, BBC News reported.

The devices are being fitted onto the seabirds that are nesting on the Farne Islands, located off the Northumberland coast.

Only 36,500 puffins were recorded in a survey from 2008, down from 55,674 in 2003, but the islands, which are home to the largest puffin colony in England, are considered a globally key site for seabirds.

David Steel, the National Trust's head warden on the Farne Islands, said the population had been increasing year-on-year and they've seen big booms in numbers.

Steel told BBC News that in 2003 they hit an all-time high of 55,500 pairs, but in 2008, the survey showed the area had lost somewhere in the region of 33 percent of breeding puffins.

The dramatic drop left scientists and conservationists puzzled and concerned for the long-term future of the species in the North Sea.

Richard Bevan, a biologist from Newcastle University who is leading the team that is now tagging the puffins on the Farnes' Brownsman Island, said a variety of devices are being attached to the birds.

He told BBC News that a lot of tagging uses satellites, where the tag transmits to the satellite and then the satellite sends the data down to the researchers' offices.

"But we cannot do that with small birds, because they will not be able to carry the weight of the devices," he said.

Guidelines stipulate that the tags cannot exceed 4 percent of the bird's weight.

Bevan said they are using GPS loggers, which are basically archival devices that store information rather than transmit it in real-time.

"The tag will record the position of the bird every minute. It will do this for about three to four days, during which time the birds will have been out on a number of foraging trips," he said.

He said once the researchers understand where the birds are going they can then begin to look at why they go there.

The team hopes to better understand where the birds go during the winter months since it is the period when many puffins are believed to disappear.

The team is using devices called geolocators, which are much smaller than GPS loggers and can be permanently fitted to a bird's leg ring"”meaning the bird can go away and do whatever it does.

"As long as it comes back at some point then we will be able to get a record of where it has been," Bevan said.

He explained that the devices are important for the out-of-breeding season because the team currently knows very little about what the birds are doing.

"If there is something that is affecting the adults, then that has serious consequences for the species," he added.

A high mortality rate among adults over just a few years can quickly destabilize the puffin population since female's only lay one egg a year.

Bevan and his team are hoping to publish initial results gathered by the GPS loggers in the fall.